Russia and France's foreign ministers disagreed sharply today over who was to blame for a chemical weapons attack in Syria.

After talks in Moscow, French Foreign Minister Laurent Fabius claimed that the UN report into the incident left no room for doubt that the Syrian government was responsible.

"When you look at the amount of sarin gas used, the vectors, the techniques behind such an attack, as well as other aspects, it seems to leave no doubt that the regime is behind it," Mr Fabius insisted.

But his Russian counterpart Sergei Lavrov insisted that Moscow had "serious grounds" to believe the attack had been a provocation by rebel forces.

Mr Lavrov said that no decision on military intervention should be made before all the evidence had been considered.

"We want objective professional assessments of the events of August 21," he said.

Careful not to blame either side for the chemical weapon attack, UN inspectors reported on Monday that rockets loaded with the nerve agent sarin had been fired from an area where Syria's military had bases, but said the evidence could have been manipulated in rebel-controlled neighbourhoods.

The US, Britain and France, eager to justify a UN resolution including the use of force, jumped at the chance to declare that President Bashar al-Assad's government was responsible.

Russia called the investigators' findings "deeply disturbing," but insisted it was too early to draw conclusions.

Claims that opposition forces were responsible "cannot be simply shrugged off," Russia's UN ambassador Vitaly Churkin insisted.

Mr Churkin questioned why there were no reports of opposition casualties if government forces fired rockets filled with sarin to try to oust them from the area.

"Is it theoretically possible to fire five or six rockets and miss your opponent?" he asked.